The study of expressions and equations helps students to transition from their work with number and operations in elementary school to the level of conceptual understanding needed for algebra. Students at this grade level also use mental computation and estimation strategies to assess the reasonableness of answers. Communicating mathematical ideas and sharing mathematical thinking are essential habits of mind. The puzzle solvers must decide how to share and organize the information so they can create an equation and find the solution. The teacher tells the outer group to identify the mathematics needed to solve the puzzle and to notice how the students work together. Amber pipes up and says that she has a card about the rate per day, and then reads her card aloud. The teacher compliments the students on their willingness to help each other clarify their thinking, especially when it’s faulty, and tells them that this kind of discussion will help them to play Equivalent Expressions.